Santa Monica Linear sits on a sloping landscaped site on the grounds of a house designed by celebrated Californian modernist Ray Kappe.
Made of steel and glass, the 30-foot-long (nine metres) artwork is a horizontal slash that reflects the sky and trees.
At night, LEDs turn it into a shifting light display that echoes the famous sunset of the beachfront California town.
Architect-turned-artist Phillip K Smith III worked with SOM's director of structural engineering Eric Long to design the site-specific piece and install it on a steep-sided hill.
"The simplicity of Smith's concept and beauty of the site posed direct challenges to the perfect implementation of the artwork," said SOM.
"Of particular importance was the 42-degree sloped site and the necessity of the 30-foot-long mirrored plane to be a perfectly level extruded form, free from internal structural elements."
During the day, the mirrored surface reflects the light and scenery. As night falls, the LED display shows a shifting array of light and colour like an artificial sky.
"At sunset, the reflection of the glowing sky and onshore moving clouds merges with floating, shifting gradients of light across the surface of the work," said Phillip K Smith III.
Mirrored projects often raise concerns about birds flying into them, but the artist said that its positioning means it poses no risk to wildlife.
"Bird strikes are not an issue as the piece," Phillip K Smith III told Dezeen.
"[The piece] reflects the sky in the midst of a wall of green landscape. Bird strikes are issues for skyscrapers, where the sky is reflected adjacent to real sky."
Santa Monica Linear sits amongst lush planting and tall eucalyptus trees, bracketed by an early Skyspace chamber by the artist James Turrell and a 40-foot-tall (12 metres) piece by the sculptor Nancy Rubins.
Santa Monica is a beachfront city in Los Angeles county, California. Local architecture includes this cactus-filled greenhouse by Part Office and the headquarters of Gwyneth Paltrow's lifestyle brand Goop.
Smith grew up in Palm Springs, California, and trained as an architect at Rhode Island School of Design before becoming an artist.
Photography is by Lance Gerber Studio.